The invention relates to a retaining element of plastic having a fastening part located therein and to a method of mounting lines on articles.
The mounting of lines, such as pipes and cables, on a foundation by means of clips is expensive and requires complicated working steps. Often, to fasten lines and the like, first of all threaded bolts or the like are attached to an article. A fitter in each case puts a plastic clip onto a threaded bolt. The lines and a mating part are then put onto the clip. Further rationalization of these operations is problematic, since the sequence of operations has to be maintained. In addition, a multiplicity of parts have to be manipulated.
An aim of the present invention is to provide a retaining element of plastic and a method for simplified mounting of lines, such as, for example, electric cables, pipes and the like.
This aim is achieved with a retaining element and a method as defined in the claims, the subclaims representing expedient developments.
Accordingly, a retaining element of plastic having at least one line receptacle and a cavity for the captive accommodation of a fastening part is provided. The fastening is no longer effected on retaining devices attached beforehand, such as threaded bolts for example. The fastening part is preferably made of metal and in particular is preferably designed as a screw.
The hole- and thread-forming screw presented in DE 39 09 725 C1 for screwing into sheet metal of a thickness up to about 1 mm is especially suitable as fastening part for fastening the retaining element according to the invention. Such a screw has a head having a tool receptacle, a threaded shank and an adjoining cylindrical part which is of a diameter lying below the effective diameter of the threaded shank and merges into a tapering hole-forming part. In this case, the threaded shank merges into the cylindrical part via a taper extending over about four thread turns. The hole-forming part ends in a crowned friction surface which corresponds to a radius of about 0.5 mm. Especially firm seating can be achieved with such a hole- and thread-forming screw, the accumulation of metal chips, which could fall into the hole produced, being avoided at the same time.
The fastening part is in particular preferably enclosed in the radial direction over its entire length by the retaining element and therefore does not project axially beyond the latter. Risk of injury due to a projecting point of the fastening part is thus avoided. The position of the preassembled fastening part can no longer be changed from outside, for example during transport. Since it is thus not possible for the front end (point) of the fastening part to project, plane-parallel bearing of the retaining element against an article can be achieved without the retaining element being distorted during assembly. This is especially important when a plurality of fastening parts which could otherwise project from the retaining element with their points are provided for attaching the retaining element to the article.
In a modification of the invention, the cavity is laterally open. In particular, at least two, preferably at least three, and preferably three openings are provided. These openings may be designed like windows. These openings are preferably designed in such a way that they run up to the free margin of the cavity. In this way, the cavity is defined by finger-like projections, there being at least two, but preferably three of such finger-like projections. These finger-like projections are preferably of symmetrical design and arranged around the cavity.
In this modification, the invention thus relates to a retaining element of plastic in which the cavity is formed by a wall provided with openings.
In this case, the wall provided with openings is preferably formed from at least two, preferably at least three, and in particular preferably three finger-like projections. For effective retention of the fastening part, the finger-like projections, in the region facing the cavity, are provided with an extension having a groove-like section for retaining the fastening part.
The retaining element is preferably designed in such a way that the finger-like projections are approximately as long as the fastening part.
This modification of the invention therefore represents a retaining element of plastic, in particular one as described above for mounting lines on an article, which retaining element has:
a. at least one line receptacle,
b. at least one location region formed from at least two finger-like projections and intended for the captive accommodation of a fastening part,
c. a retaining location device located in the location region and intended for accommodating and retaining the fastening part in a preassembly position,
d. a tool entry opening of the location region on that side of the retaining element which is remote from the article,
e. a bearing surface, serving as final assembly position, on the bottom of the location region for a head of the fastening part.
The fastening of the retaining element according to the invention does not require the same precision as the placing of a clip at a point which is exactly predetermined, for example by an attached threaded bolt. Simple assembly is possible on account of the fastening part captively preassembled in the retaining element. No mating part has to be put onto a first clip. It is merely necessary to slip the retaining element onto one or more lines, to place this system in position and to anchor the fastening part to the relevant article. Apart from the lines to be fastened and having retaining elements, no further part has to be moved. On account of the simple working steps and the reduced requirement for precision during assembly, the system is readily suitable not only for manual assembly but also for semi-automatic or fully automatic assembly. The preassembled system, consisting of the lines with retaining elements attached thereto, can be delivered from suppliers to the manufacturer so as to suit a corresponding article, e.g. lines fitted with retaining elements for the cooling unit of a refrigerator. At the manufacturer""s, the system need only be placed in position on the article and fastened or screwed thereto.